Method and apparatus for muting signaling in a wireless communication network

ABSTRACT

In one aspect, the present invention provides a simple method of signaling reference signal muting information to receiving radio equipment, such as items of user equipment (UEs). The reference signals may be positioning reference signals and/or cell-specific reference signals, for example. In one or more embodiments, the present invention proposes a general solution whereby the receiving radio equipment is informed not only on whether muting is used in general in a cell, but also the particular timing and formatting of such muting. Further, the contemplated method provides for the use of dynamic muting patterns, and thus avoids the need for statically defined muting patterns, and provides for coordinated muting control, across two or more network cells. In at least one embodiment, static or less dynamic aspects of the muting configuration is signaled via higher-layer signaling, while lower-layer signaling is used to signal more dynamic aspects of the muting configuration.

RELATED APPLICATIONS

This application is a divisional filing of pending U.S. patentapplication Ser. No. 12/858,809 filed on 18 Aug. 2010, which claimspriority from the U.S. provisional patent application No. 61/314,724filed on 17 Mar. 2010.

FIELD OF THE INVENTION

The present invention generally relates to interference management inwireless communications networks, and particularly relates tocontrolling the muting of reference signals transmitted by one or morebase stations in the network and signaling related muting configurationinformation.

BACKGROUND

Wireless communication networks use reference signal transmissions tosupport a variety of key functions. In this regard, a “reference” signalprovides receiving radio equipment with some type of referenceinformation—timing, frequency, phase, etc.—that enables certainmeasurements by the receiving equipment. For example, cell-specificreference signals, also referred to as common reference signals or CRSsprovide receiving radio equipment with a basis for estimatingpropagation channel conditions. Other physical-layer reference signalsinclude so called positioning reference signals or PRSs, which areparticularly contemplated for newer, more capable networks, such asthose based on the 3GPP Long Term Evolution (LTE) standards.

Release 9 of LTE, for example, contemplates the use of PRSs to enableand improve the burgeoning host of positioning-dependent services thatare or will be offered in such networks. That is, beyond the lawenforcement and safety requirements associated with positioning mobilestations and other user equipment, there is an increasing range ofpositioning-dependent applications and services, all relying on theability of these newer wireless communication networks to efficientlyand accurately support positioning services.

Indeed, the possibility of identifying user geographical location in thenetwork has enabled a large variety of commercial and non-commercialservices, e.g., navigation assistance, social networking, location-awareadvertising, emergency calls, etc. Different services may have differentpositioning accuracy requirements imposed by the application. Inaddition, some regulatory requirements on the positioning accuracy forbasic emergency services exist in some countries, i.e. FCC E911 in theU.S.

In many environments, the position can be accurately estimated by usingpositioning methods based on GPS (Global Positioning System). However,contemporary networks also often have the possibility to assist UEs inorder to improve the terminal receiver sensitivity and GPS startupperformance (Assisted-GPS positioning, or A-GPS). GPS or A-GPSreceivers, however, may not necessarily be available in all wirelessterminals. Furthermore, GPS is known to have a high failure incidence inindoor environments and urban canyons. A complementary terrestrialpositioning method, called Observed Time Difference of Arrival (OTDOA),has therefore been standardized by 3GPP. Correspondingly, PRSs play akey role in OTDOA measurements.

With OTDOA, the receiving radio equipment measures the timingdifferences for reference signals received from multiple distinctlocations. For each (measured) neighbor cell, the equipment measuresReference Signal Time Difference (RSTD), which is the relative timingdifference between a neighbor cell and the reference cell. The positionestimate for the receiving equipment is then found as the intersectionof hyperbolas corresponding to the measured RSTDs. At least threemeasurements from geographically dispersed base stations with a goodgeometry are needed to solve for two coordinates of the receivingequipment and the receiving equipment clock bias.

More particularly, to solve for position, precise knowledge of thetransmitter locations and transmit timing offset is needed. Positioncalculation can be conducted, for example, by a positioning server(eSMLC in LTE) or by the receiving equipment, which often is an item ofuser equipment (UE), such as a mobile terminal or other type of portablecommunication device. The former approach is referred to as aUE-assisted positioning mode, while the latter is a UE-based positioningmode. As noted, LTE has introduced the use of new physical signalsdedicated for positioning (PRSs), as defined in 3GPP TS 36.211, “EvolvedUniversal Terrestrial Radio Access (E-UTRA); Physical Channels andModulation Positioning Reference Signals.”

PRSs generally are transmitted from one antenna port from a given basestation for a corresponding cell according to a pre-defined pattern. Afrequency shift, which is a function of the physical cell identity orPCI, can be applied to the specified PRS patterns, to generateorthogonal patterns and modeling an effective frequency reuse of six.Doing so makes it possible to significantly reduce neighbor cellinterference as measured on the PRS for a given cell. Interferencereduction on the PRS measurements correspondingly leads to improvedpositioning measurements.

Even though PRSs have been specifically designed for positioningmeasurements and in general are characterized by better signal qualitythan other reference signals, the current LTE standard does not mandateusing PRSs. Other reference signals, the earlier mentioned CRSs can, inprinciple, be used for positioning measurements.

If PRSs are used, they are transmitted in pre-defined positioningsubframes grouped by several consecutive subframes, with N_(PRS)subframes in each positioning occasion. The positioning occasions arerecurring, e.g., repeated according to a defined periodic intervalhaving a certain periodicity of N subframes. According to 3GPP TS36.211, the standardized periods for N are 160, 320, 640, and 1280 ms,and the number of consecutive subframes N_(PRS) that define eachpositioning occasion are 1, 2, 4, and 6.

Because OTDOA-based positioning requires that PRSs be measured frommultiple distinct locations, a receiving radio apparatus (user equipmentor other radio node in the network) may have to work with a wide rangeof received signal strengths, e.g., the PRSs received from neighboringcells may be significantly weaker than the PRSs received from a servingcell. Furthermore, without at least approximate knowledge of whenparticular ones of the PRSs are expected to arrive in time and what PRSpatterns are being used (e.g., arrangements within the time-frequencygrid of OFDM signal subframes), the receiving radio apparatus isobligated to perform PRS searching within potentially largetime-frequency windows. That, of course, increases the processingresources and the time needed for making PRS measurements, and tends tolower the accuracy of the results.

To facilitate such measurements, it is known for the network to transmitassistance data, which includes, among other things, reference cellinformation, neighbor cell lists containing PCIs of neighbor cells, thenumber of consecutive downlink subframes that constitute a positioningoccasion, and the overall transmission bandwidth used for PRStransmission, frequency, etc.

Further, it is known to mute PRSs, where “muting” means transmittingwith zero power (or low power) at certain positioning occasions. Suchmuting applies to all PRS resource elements—i.e., defined OFDMsubcarriers at defined symbol times—within the same subframe and overthe entire PRS transmission bandwidth. However, to date, the 3GPPstandards do not specify how muting is to be implemented, nor do theyspecify signaling for communicating muting information to UEs or otherreceiving equipment that might be making use of the PRSs beingtransmitted by a given cell or a given cluster of neighboring cells.

Certain muting arrangements, however, have been contemplated. Onecontemplated approach is to use random muting by cells. Here, eacheNodeB decides whether or not to mute its PRS transmissions for a givenpositioning occasion (or occasions) according to some probability. Inthe most basic contemplation of this approach, each eNodeB (cell) in thenetwork independently makes muting decisions (according to some definedprobability), without any coordination between the cells. Theprobability used to make the muting decision is statically configuredper eNodeB or per cell.

While this approach offers certain advantages in terms of simplicity onthe network side, it leaves receiving radio equipment with the sameburdensome processing tasks, as said equipment has no knowledge of therandom muting operations. A further issue is the inability to know theoptimal probabilities to use for making the muting decision, and thefact that such probabilities likely change in dependence on complexinterrelationships between cells (varying geometry, etc.), and may evenchange depending upon times of day, etc.

Another approach relies on a limited set of muting patterns, and mapsthese patterns according to PCIs. This approach allows a UE or otherradio receiver to determine when PRSs are transmitted (or muted) in anygiven cell of interest, based on receiving information regarding theassociation between muting patterns and PCIs—e.g., a table. However,this approach requires signaling the actual patterns or hard-coding theminto the receiving equipment. That latter approach may not be practicalfor some types of equipment. Besides, the static nature of such mappinghas its own disadvantages.

Another approach proposes sending UEs an indication of whether or notautonomous muting is activated. A Boolean indicator is transmitted forthe reference cell and also all neighbor cells as a part of theassistance data. When the indicator is FALSE, the UE can avoid blinddetection of PRS muting, optimize detection thresholds and thus improvethe positioning performance. However, with the indicator set to TRUE,the UE still does not receive information indicating when and for whichresource blocks (RBs) muting occurs, meaning that the UE still needs toblindly detect when PRS muting is used in each cell.

SUMMARY

In one aspect, the present invention provides a simple method ofsignaling reference signal muting information to receiving radioequipment, such as UEs. (The reference signals may be, e.g., PRSs and/orCRSs.) In one or more embodiments, the present invention proposes ageneral solution whereby the receiving radio equipment is informed notonly on whether muting is used in general in a cell, but also theparticular timing and formatting of such muting. Further, thecontemplated method provides for the use of dynamic muting patterns, andthus avoids the need for statically defined muting patterns, andprovides for coordinated muting control, across two or more networkcells.

Accordingly, in one embodiment, the present invention comprises a methodof controlling the transmission of reference signals in a wirelesscommunication network. The method includes transmitting referencesignals at recurring occasions, for use in making reference signalmeasurements at receiving radio equipment. The method further includesmuting the reference signals in certain ones of the occasions, inaccordance with a muting configuration, and transmitting mutingconfiguration information indicating said muting configuration, toinform the receiving radio equipment regarding one or more aspects ofsaid muting.

In particular, the muting configuration information includes one or moreof: a bandwidth parameter identifying the portion of reference signalbandwidth to which muting applies; a subframes parameter indicating thenumber of consecutive subframes within an occasion to which mutingapplies; and a muting occasion parameter indicating occasions to whichmuting applies. (In at least one embodiment, in cases where no mutingbandwidth parameter is signaled, the receiving radio equipment isconfigured to assume that muting is applied over the entire referencesignal transmission bandwidth.) Such information allows the receivingradio equipment—network node, UE, or other radio apparatus—to knowexactly when and how reference signals are muted. In turn, thatknowledge provides for improved accuracy in acquiring and measuringreference signals, and for reduced processing complexity through, forexample, the elimination or reduction in blind searching.

In another embodiment, the present invention comprises a base stationfor use in a wireless communication network that transmits referencesignals in a wireless communication network. The base station includes atransmitter configured to transmit reference signals at recurringoccasions, for use in making reference signal measurements at receivingradio equipment, and a processing circuit that is operatively associatedwith the transmitter and configured to mute the reference signals incertain ones of the occasions, in accordance with a mutingconfiguration. In particular, the processing circuit is configured totransmit, via said transmitter, muting configuration informationindicating the muting configuration, to inform the receiving radioequipment regarding one or more aspects of the muting.

In yet another embodiment, the present invention comprises a method andapparatus in a positioning node that is configured for use with awireless communication network. The positioning node includes one ormore processing circuits configured to determine a muting configurationused to control muting of positioning reference signals transmitted atrecurring positioning occasions from one or more base stations in thewireless communication network. In one embodiment, the positioning nodedetermines the muting configuration based on signaling received from thebase station(s), i.e., the base stations inform the positioning node asto their muting configuration(s). In at least one such embodiment, thepositioning node generates muting configuration information based on thesignaling received from the base station(s), and it sends this mutingconfiguration information as higher-layer signaling, to assist radioequipment with measuring the positioning reference signals transmittedfrom the base stations, in accordance with the muting configurations ofthose base stations.

In another embodiment, the one or more processing circuits areconfigured to decide the muting configuration(s) to be used—here,“determining” the muting configurations of the one or more basestation(s) means generating the muting configuration information at thepositioning node. In at least one such embodiment, the positioning nodeis configured to send muting control signaling to the base station(s),to effect muting control in accordance with the determined mutingconfigurations.

In either case, the positioning node further includes a communicationinterface operatively associated with the one or more processingcircuits. This communication interface, which may incorporate more thanone physical interface and/or signaling protocols, is configured forsending the muting configuration information and/or sending the mutingcontrol signaling, and, in applicable embodiments, receiving signalingfrom the base stations indicating their muting configuration(s). Itshould be understood that such signaling between the positioning nodeand the base stations may be direct or indirect.

In at least one embodiment, the one or more processing circuits areconfigured to generate muting configuration information that indicateswhen or how muting will be applied by the one or more base stations, forindicated or known positioning occasions. The positioning node sendscorresponding muting configuration information as higher-layersignaling, for transmission by the one or more base stations to radioequipment receiving the positioning reference signals.

In another embodiment, a base station is configured to generate themuting configuration and send it to a positioning node. In turn, thepositioning node sends this information as assistance data—e.g., thepositioning node sends positioning reference signal measurementassistance data to an item of user equipment. The BS then applies thegenerated muting configuration, i.e., it transmits or does not transmitreference signals accordingly. In this same embodiment and/or others,the base station is equipped with an interface over which the mutingconfiguration is exchanged with other base stations, to provide fordistributed coordination of muting configurations.

In another embodiment, the present invention provides a method andapparatus, for controlling measurement of reference signals at areceiving radio apparatus. The reference signals are transmitted by awireless communication network at recurring occasions, and the receivingradio apparatus is, for example, a UE or another node in the network.

In any case, the contemplated method includes receiving signaling fromthe wireless communication network that conveys one or more of thefollowing muting parameters: a bandwidth parameter identifying theportion of reference signal bandwidth to which muting applies; asubframes parameter indicating the number of consecutive subframeswithin an occasion to which muting applies; and a muting occasionparameter indicating occasions to which muting applies. Correspondingly,the method includes controlling reference signal measurement by theradio apparatus, in accordance with the received muting parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one embodiment of a wireless communicationnetwork.

FIG. 2 is a logic flow diagram of one embodiment of a method of mutingreference signals in accordance with a muting configuration, andtransmitting corresponding muting configuration information.

FIG. 3 is a block diagram of one embodiment of a base station, e.g., aneNodeB in an LTE network.

FIG. 4 is a block diagram of one embodiment of a muting control node,that provides muting control for one or more cells in a wirelesscommunication network.

FIGS. 5A-C are logic flow diagrams of various embodiments of a method ofdetermining muting configurations and corresponding muting control, andsending corresponding muting control information.

FIG. 6 is a logic flow diagram of one embodiment of a method ofreceiving muting configuration information (muting parameters) at userequipment or other radio equipment making reference signal measurements,and controlling such measurements according to the received mutingparameters.

FIG. 7 is a block diagram of one embodiment of a radio apparatus (e.g.,UE or other radio equipment) that is configured to receive mutingconfiguration information and to control its measurements of referencesignals according to that information.

FIGS. 8 and 9 are diagrams illustrating different embodiments forapplying muting to a subset of subframes within a given reference signaltransmission occasion in which the reference signals span a number ofsubframes.

FIG. 10 is an example table of muting configuration parameter values,which can be used for configuring the muting of positioning referencesignals.

DETAILED DESCRIPTION

As a non-limiting example, FIG. 1 illustrates one embodiment of awireless communication network 10, which includes a Radio Access Network(RAN) 12 and an associated Core Network (CN) 14. The RAN 12 includes anumber of base stations 16, e.g., BS 16-1, 16-2, and so on. Unlessneeded for clarity, the reference number 16 is used to refer to BSs 16in both singular and plural senses. Each BS 16 provides one or more“cells” 18, e.g., cell 18-1 corresponding to BS 16-1, cell 18-2corresponding to BS 16-2, and so on. The cells 18 represent the radioservice coverage provided by each BS 16, for supporting communicationswith user equipment 20, e.g., UE 20-1, UE 20-2, and so on.

Correspondingly, the CN 14 communicatively links the UEs 20 to eachother and/or to communications equipment in other networks, such as theInternet, the PSTN, etc. To that end, the CN 14 includes a number ofnodes or other functional entities. By way of simplified example, theillustrated CN 14 is depicted as including a Serving Gateway (SGW) 22, aMobility Management Entity (MME) 24, and a Positioning Node 26. In oneor more embodiments where the network 10 comprises an LTE network, or anLTE advanced network, the positioning node 26 comprises an E-SMLC orSLP, or another type of network-based positioning node.

To support positioning operations, e.g., OTDOA measurements, the network10 in one or more embodiments transmits PRSs at recurring positioningoccasions, e.g., at periodic frame/subframe intervals. In the same orother embodiments, the network 10 transmits CRSs at recurring occasions.Correspondingly, in at least one embodiment the present inventionprovides a method of controlling the transmission of reference signals(RSs) within the network 10 (e.g., within all or a portion of thenetwork).

As shown in FIG. 2, the method 200 includes transmitting RSs atrecurring occasions, for use in making reference signal measurements atreceiving radio equipment (Block 202); muting the reference signals incertain ones of the occasions, in accordance with a muting configuration(Block 204); and transmitting muting configuration informationindicating said muting configuration, to inform said receiving radioequipment regarding one or more aspects of said muting (Block 206). Inat least one such embodiment, the muting configuration informationincludes one or more of: a bandwidth parameter identifying the portionof reference signal bandwidth to which muting applies; a subframesparameter indicating the number of consecutive subframes within anoccasion to which muting applies; and a muting occasion parameterindicating occasions to which muting applies.

FIG. 3 illustrates an example embodiment of a base station 16, which isconfigured to implement method 200, or variations of it. In particular,the base station 16 is configured for use in a wireless communicationnetwork that transmits reference signals, and it comprises: atransmitter configured to transmit reference signals at recurringoccasions, for use in making reference signal measurements at receivingradio equipment. Here, the transmitter is included in the transceivercircuits 30, which may comprise OFDM (with or without MIMO) radiotransmission and reception circuits.

The base station 16 further includes a number of communication andcontrol circuits 32, including a processing circuit operativelyassociated with the transmitter and configured to mute the referencesignals in certain ones of the occasions, in accordance with a mutingconfiguration. Here, the processing circuit comprises, e.g., one or morereference signal (RS) muting control circuits 34, which may be one ormore microprocessor based circuits, or other digital signal processingcircuits.

In particular, the processing circuit is configured to transmit, viasaid transmitter, muting configuration information indicating saidmuting configuration, to inform said receiving radio equipment regardingone or more aspects of said muting, and wherein the muting configurationinformation includes one or more of: a bandwidth parameter identifyingthe portion of reference signal bandwidth to which muting applies; asubframes parameter indicating the number of consecutive subframeswithin an occasion to which muting applies; and a muting occasionparameter indicating occasions to which muting applies.

The base station 16 further includes a core network communicationinterface 36 for receiving muting control signaling from a higher-layernode in the wireless communication network 10, e.g., from thepositioning node 26. Further, the processing circuit is configured todetermine or otherwise set the muting configuration of the base station16, based at least in part on said muting control signaling receivedfrom the higher-layer node. In one embodiment, the core networkcommunication interface 36 provides for communicating directly orindirectly with one or more core network nodes, including a positioningnode 26, and the base station 16 is configured to receive signaling fromthe positioning node 26 that sets or otherwise controls one or moreaspects of the muting configuration of the base station 16.

As an example, the illustrated base station 16 comprises an eNodeB,where the network 10 comprises an LTE network, or LTE Advanced network.Here, as an example, the muting control signaling received at the basestation 16 comprises signaling from an E-SMLC (as the positioning node26) which controls one or more aspects of the muting configuration ofthe base station 16.

Further, in at least one embodiment, the base station 16 is configuredto transmit, via lower-layer signaling, the previously noted mutingoccasion indicator as a flag or other indicator indicating whethermuting will be used in an indicated or known occasion, and to transmit,via higher-layer signaling, one or both of the bandwidth and subframesparameters, to complement the lower-layer signaling of the mutingoccasion parameter. This arrangement is advantageous, for example,because it allows lower-overhead signaling of the muting occasionindicator, which may be more dynamic than the bandwidth/subframe detailsof muting. In any case, such signaling allows for the receiving radioequipment to be apprised of whether muting applies to a given occasionvia the muting occasion parameter (via lower-layer signaling), andapprised of the reference signal bandwidth and the number of consecutivesubframes (via higher-layer signaling), to which such muting applies forthat given occasion.

In other contemplated embodiments, the base station 16 comprises a homeeNodeB (e.g., for residential use), a pico base station (e.g., forproviding small-cell coverage), or a relay node (e.g., for extendingbase station coverage). Regardless, in at least one embodiment, the basestation includes an inter-base-station communication interface 38 and isconfigured to determine one or more aspects of the muting configurationcooperatively, with one or more neighboring base stations 16, based onexchanging inter-base-station signaling via the inter-base-stationcommunication interface 38. Of course, as noted, in at least oneembodiment, the processing circuit (e.g., RS muting control circuit(s)34) is configured to determine the muting configuration to be used bythe base station 16, and that determination is made autonomously in atleast one embodiment.

Returning to the method 200 introduced in FIG. 2, in one or moreembodiments, the reference signals (RSs) are positioning referencesignals (PRSs) transmitted at defined positioning occasions by at leastone base station 16 in the network 10, where the PRSs are used by thereceiving radio equipment in making positioning-related measurements.

Further, in at least one embodiment, “muting” the reference signals inany given occasion comprises transmitting the reference signals at zeroor reduced power. Here, “reduced” power is a transmit power below thatwhich would be used in the absence of muting, and preferablysignificantly below the “normal” levels of transmit power used fortransmitting references signals when they are not muted.

Still further, in at least one embodiment, the method relates to aplurality of base stations 16 associated with respective ones in aplurality of associated cells 18, and further comprises determining themuting configuration cooperatively across the plurality of associatedcells 18. In at least one such embodiment, determining the mutingconfiguration cooperatively across the plurality of associated cells 18comprises determining one or more muting patterns to be used across theplurality of associated cells 18. Further, in at least one suchembodiment, each base station 16 in the plurality of base stations 16transmits muting occasion indicators, in accordance with the one or moremuting patterns. That is, the muting occasion indicators as transmittedare dynamically updated to reflect the muting pattern(s).

Broadly, the method 200 may be carried out, for example, at one or moreof the base stations 16 illustrated in FIG. 1, or in an even largerplurality. In at least one embodiment, each base station 16 autonomouslydetermines its muting configuration, and correspondingly transmitsmuting configuration information. Also, in at least one embodiment, abase station 16 is configured to determine its muting configuration andsend signaling to another node that is configured to send signaling thatindicates the base station's muting configuration. As one example, thebase station 16 determines its muting configuration and sends signalingto a positioning node 26. In turn, the positioning node 26 sendssignaling to one or more UEs 20 that indicates the base station's mutingconfiguration. e.g., the positioning node 26 includes mutingconfiguration information in the positioning reference signal assistancedata that it sends to the UEs 20 by way of higher-layer signaling thatis carried through one or more base stations 16.

In such an embodiment, or in yet another embodiment, two or more basestations 16 exchange muting configuration information—e.g., LTE eNodeBscommunicating through their X2 interfaces. In at least one suchembodiment, the two or more base stations 16 cooperatively determine themuting configurations to be used by each one of them, or at least sharetheir respective muting configurations with each other. In yet anotherembodiment, another node (or nodes) in the network, other than the basestations 16, determines at least part of the muting configuration, andthe base stations 16 implement that configuration accordingly.

For example, FIG. 4 illustrates a muting control node 40, which may be,for example, the positioning control node 26 shown in FIG. 1. The mutingcontrol node 40 is configured to provide per-cell or cooperativelydetermined muting control (i.e., muting control that is coordinatedacross two or more cells). In the illustration, the muting control node40 provides muting control for three example cells, 18-1, 18-2, and18-3. Notably, the muting control node 40 is, in one or moreembodiments, configured to control the muting of one or more types ofreference signals that are transmitted in the cells 18, and configuredto send (e.g., transparently through the associated base stations 16)muting control information, so that receiving radio equipment isinformed of the muting configuration.

The illustrated embodiment of the node 40 comprises one or moreprocessing circuits 42 that are configured to generate muting controlsignaling for controlling muting of reference signals transmitted atrecurring positioning occasions from one or more base stations 16 in theRAN 12 of the network 10. Further, a communication interface 44 isoperatively associated with the one or more processing circuits 42 andthe processing circuits 42 use the communication interface 44 to sendthe muting control signaling to the one or more base stations 16.

In at least one embodiment, of the node 40, the one or more processingcircuits 42 are further configured to generate muting configurationinformation that indicates when or how muting will be applied by the oneor more base stations 16, for indicated or known occasions, and to sendthe muting configuration information as higher-layer signaling, fortransmission by the one or more base stations 16 to radio equipmentreceiving the reference signals (e.g., UEs 20 and/or other nodes in thenetwork 10).

Further, as noted, in at least one embodiment, the one or moreprocessing circuits 42 are configured to control muting of the referencesignals in coordinated fashion across two or more cells 18 of the radioaccess network, said two or more cells 18 associated with said one ormore base stations 16. In at least one such embodiment, the one or moreprocessing circuits 42 are configured to coordinate, as across the twoor more cells 18, at least one of the following: the timing or selectionof which reference signal occasions have muting applied to them; thereference signal bandwidth to which muting is applied in one or more(reference signal transmission) occasions; and the number of consecutivesubframes to which muting is applied within a given occasion.

FIG. 5A illustrates a method 500A implemented, for example, at the node40, corresponding to the above-described structural configuration of thenode 40. The method 500A includes controlling muting of RSs in one ormore cells 18 of the network 10 (Block 502)—e.g., a method where a nodeacts in some centralized sense as a muting configuration controller forthe RSs being transmitted in two or more cells 18 in the network 10. Theillustrated method 500A further includes sending higher-layer signaling,conveying (at least some of) the muting configuration information,corresponding to the muting control, for transmission to receiving radioequipment (Block 504), e.g., to the UEs 20 operating in the one or morecells 18.

As an example, the higher layer signaling comprises Radio ResourceControl (RRC) or LPP signaling. In a particular example, certain aspectsof the muting configuration are configured using higher-layer signaling.Example aspects include muting bandwidth information. In at least onesuch embodiment, other aspects of the muting configuration are signaledusing lower-layer signaling, such as physical layer signaling and/or MAClayer signaling. Lower-layer signaling is advantageous, for example,when signaling frequently changing aspects of the muting configuration,such as the muting occasion indicators.

FIGS. 5B and 5C show variations of the method 500A, which may beadvantageously carried out at a positioning node 26, such as an E-SMLCin an LTE network. For example, in the method 500B, one sees apositioning node 26 that is configured to determine the mutingconfiguration of one or more base stations 16, based on receivingsignaling (directly or indirectly) from the base stations 16, where thatsignaling indicates the muting configuration(s) of the base stations 16(Block 506). Correspondingly, the positioning node 26 sends higher-layersignaling conveying muting configuration information (Block 508), e.g.,indicating the muting configuration in use at the base station(s) 16.That higher-layer signaling targets radio equipment, e.g., UEs 20, toassist them in making positioning reference signal measurements withrespect to the base station(s) 16, in accordance with the mutingconfiguration(s) of the base station(s) 16.

Thus, the method 500B can be understood as an embodiment where one ormore base station(s) 16 individually or cooperatively determine theirmuting configurations while communicating e.g. over the X2 interface,and one or more of them send signaling to the positioning node 26, toinform the positioning node 26 of the muting configurations. Becausecertain aspects of the muting configuration are advantageously signaledvia higher-layer signaling, receiving such signaling from the basestations 16 allows the positioning node 26 to generate correspondingmuting configuration information that it then sends to targeted UEs 20or other radio equipment, to inform those recipients of the mutingconfiguration(s) in use at the base stations 16.

FIG. 5C illustrates an alternative method 500C, where the positioningnode 26 determines the muting configuration(s) not based on the basestation(s) 16 informing it of the decided configurations, but rather onthe positioning node itself deciding the muting configuration(s) to beused by the base station(s) 16 (Block 510). As a non-limiting example,this embodiment is advantageous in implementations where coordination ofmuting configurations across two or more cells 18 of the network 10 isdesired—e.g., a positioning node 26 can provide centralized control andcoordination of the muting configurations used by any one or more groupsof base stations 16, based on being provisioned with base-station/cellneighbor information, etc.

In any case, the method 500C further includes the positioning node 26generating/sending muting control signaling to the base station(s), toeffect muting control in accordance with the muting configuration(s)decided by the positioning node 26 (Block 512). Note, too, that in onesuch embodiment, the base stations 16 send all muting configurationinformation as lower-layer signaling, to assist radio equipment withmeasuring their reference signals in accordance with the mutingconfigurations. That is, although the positioning node 26 determines allor at least some aspects of the muting configuration(s) used by the basestation(s) 16, the base stations themselves generate and send thelower-layer signaling used to convey the corresponding mutingconfiguration to the receiving radio equipment.

However, in another embodiment, the positioning node 26 again decidesall or some aspects of the muting configuration(s) to be used by thebase station(s) 16. However, the positioning node 26, in addition tosending control signaling to the base station(s) 16 to implement themuting configuration(s) at those base stations 16, also sendshigher-layer signaling to one or more UEs 20 or other receivingequipment. As before, that higher-layer signaling indicates some or allaspects of the muting configuration(s) used by the base station(s) 16.

As for the receiving radio equipment—i.e., equipment that receives thereference signals and acts on the muting configuration information—FIG.6 illustrates an example processing method 600. The illustrated method600 includes receiving signaling conveying one or more muting parameters(Block 602). (As previously described, these muting parameters indicateone or more aspects of the muting configuration—i.e., they inform thereceiving radio equipment of the muting configuration used to controlreference signal muting.) The receiving radio equipment includesprocessing circuitry that is configured to interpret the received mutingcontrol information, and to correspondingly control its reference signalmeasurements, according to the received muting parameters (Block 604).

Correspondingly, FIG. 7 illustrates an example embodiment of receivingradio equipment 50, which may be configured to implement the method 600of FIG. 6, or variations of that method. The equipment 50 includestransceiver circuits 52, e.g., a wireless communication transceivercomprising MIMO/OFDM transmitter and receiver circuitry for LTEcommunications. The equipment 50 further comprises communication andcontrol circuits 54, which comprise, for example, fixed and/orprogrammable circuitry, such as one or more microprocessor-basedcircuits.

The circuits 54 include reference signal (RS) acquisition and processingcontrol circuitry 56, including received RS muting information detectionand processing circuitry 58. With this configuration, the equipment 50configures one or more aspects of its reference signal measurementoperations according to muting control information received from thenetwork 10, via its transceiver circuits 52. For example, it may foregoreference signal measurements for certain cells on certaintime/frequency resources, based on its knowledge that muting is appliedat those times and/or frequencies. Further, it may make more accuratemeasurements of the received reference signals, based on knowing whichtime/frequency resources within particular subframes to which muting isapplied, and/or based on knowing which cell reference signals are muted,how they are muted, and when they are muted. Note that in one or moreembodiments, “muting” a reference signal comprises the transmitting nodereducing the transmit power allocated to that signal, where suchreduction is potentially significant (e.g., in terms of dBs, as comparedto non-muted transmission power). The power offset value or indicatorused for such reduction can be signaled.

In at least one embodiment, one or more of the UEs 20 are configuredaccording to the example of FIG. 7. However, it should be understoodthat other nodes in the network 10 also may be configured to receivemuting configuration information, and to control their own acquisitionand processing of reference signals according to that received mutingconfiguration information.

For example, the equipment 50 receives signaling from the network 10that conveys one or more of the following muting parameters: a bandwidthparameter identifying the portion of reference signal bandwidth to whichmuting applies; a subframes parameter indicating the number ofconsecutive subframes within an occasion to which muting applies; and amuting occasion parameter indicating occasions to which muting applies.(Note that FIG. 8 illustrates muting the middle portion of a givenreference signal bandwidth, and FIG. 9 illustrates muting the outerportions of a given reference signal bandwidth.) Correspondingly, theequipment 50 controls its reference signal measurements, in accordancewith the received muting parameters.

In detailing the possibilities for providing receiving radio equipmentwith those muting parameters in the context of PRSs, it is contemplatedherein to provide UEs 20, and other radio apparatuses that receive andmake measurements on the reference signals, with knowledge about thepositioning reference configuration in a cell 18 (reference signals tobe measured, their transmission bandwidth, subframes for positioningmeasurements and their periodicity, etc.). This assumption is relevantfor the serving cell 18, but also neighbor cells 18 that the UE may havedetected blindly (even for reasons other than mobility, i.e., notnecessarily for positioning purposes).

As noted, the muting configuration information can be provided usinglower-layer signaling, higher-layer signaling, or some combination oflower-layer and higher-layer signaling. As an LTE-based example oflower-layer signaling, prior to every positioning occasion, each eNodeBsends a command or an indicator (e.g. one bit) to the UEs 20 vialower-layer signaling such as in a Medium Access Control (MAC) ProtocolData Unit (PDU), or as a part of the scheduling information, which mapsto the Physical Downlink Control Channel (PDCCH). Thus, lower-layersignaling in this example can be understood as some form of controlchannel signaling, carrying information related to the physical layer(L1) or Layer 2, such as MAC.

In LTE, L1/L2 control information is sent via PDCCH, and UEs 20 arerequired to decode the PDCCH, which is sent in every subframe, so thatthe UEs 20 acquire scheduling information etc. In one embodiment herein,it is proposed to send a 1-bit command in each cell 18, via lower-layersignaling, indicating whether muting will or will not be used in thecell 18 during the next positioning occasion. In general, mutingconfiguration signaling may refer by default to an “indicated”positioning occasion, which may be signaled to the UEs 20, or known tothe UEs 20, such as based on the UEs being configured to use a defaultassumption that the signaled muting configuration information pertainsto the next positioning occasion.

In an example command configuration, “0” or other such indication meansmuting is NOT used in the cell 18, in the next occasion and “1”therefore means that muting is used in the next positioning occasion.The opposite logical meanings obviously can be used, or another approachto indicating the used/not-used status of muting for each mutingoccasion.

However, in one embodiment, each base station 16 is configured to sendthe command only if the base station's corresponding cell 18 will bemuted in the next occasion. Otherwise, i.e., in the absence of thecommand, the UEs 20 (or other receiving radio equipment) assume thatmuting will not be used in the cell 18 during the next positioningoccasion. Further, the UEs 20 or other receiving equipment may beconfigured to maintain the assumption that muting is not used, until thereception of the next command indicating that muting will be used.

Advantageously, the UEs 20 or other receiving radio equipment do nothave to perform blind detection when muting is used—that is, theknowledge that muting is applied to reference signals during a givenreference signal transmission occasion allows the receiving radioequipment to forego blind searching. Eliminating blind detectionsignificantly reduces UE complexity, lowers UE power consumption anddecreases UE processing requirements.

In another embodiment, the subframes during which PRSs can be mutedwithin a positioning occasion are known a priori to the UEs 20 and thenetwork 10. For example, if muting is indicated for a given positioningoccasion, then the UEs can assume that this applies to all subframeswith the indicated positioning occasion. Alternatively, muting may applyonly to specific subframes of the indicated occasion. For example, onlythe first or second half of a given positioning occasion will be muted.Whether the first or second half is muted may be known or otherwise setaccording to cell IDs, for example.

The above described muting indicator may be a 1-bit command, and serveas a type of ON/OFF signaling. Under low signal quality (e.g. low SNR,high BER, low received power, etc.) the receiving radio equipment maynot be able to reliably detect the muting indicator command. This issuemay lead a UE 20 or other receiving radio equipment to make a falsedecision—i.e., an erroneous conclusion about whether muting will or willnot be used for a given occasion.

As an advantageous mitigation technique, however, it is proposed hereinto configure UEs 20 or other receiving radio equipment to adopt adefined default behavior. For example, under unreliable conditions,e.g., as determined by the UE 20 based on unreliable reception of themuting indicator, or based on other reception quality measurements orindicators, the UE 20 may be configured to assume that muting is notused for the occasion for which the decision is being taken (i.e., thenext occasion, or a known future occasion). This configuration has theadvantage of detecting and measuring reference signals for the occasionat issue, but also may result in the UE 20 searching for referencesignals that are, in fact, muted for the occasion at issue. Thus, analternate mitigation technique is based on configuring the UEs 20 toassume that muting is used. That is, in cases where a given UE 20determines that the muting indicator is unreliably received, that UE 20makes the default determination that muting will be used for thepositioning occasion at issue (i.e., the next occasion, or some otherknown future occasion).

Additionally, the UE 20 is, in one or more embodiments contemplatedherein, configured to collect statistics on the unreliably detectedmuting indication commands over a certain time and report the results tothe network 10. In turn, the network 10 is configured to use suchinformation as the basis for determining that the transmit power of themuting indication commands should be increased or decreased. Increasingthe power improves reception and thus that decision is taken when thereliability statistics indicate an unacceptably high unreliability.Conversely, decreasing the power reduces inter-cell and intra-cell (ifpresent) interference and that decision thus is taken when thereliability statistics indicate reliability that is better than needed,e.g. by comparing the number or the ratio of erroneous muting commandsto a threshold.

Such power control is, in at least one embodiment, implemented at theindividual base station 16, where processing circuitry (e.g., the RSmuting control circuits 34, shown in FIG. 3) at the base station 16 isconfigured to evaluate the reliability statistics for muting indicatorreception from at least one UE 20, and preferably multiple UEs 20, andto control transmit power increases and decreases based on thatevaluation. Note, here, that the transmit power control increases anddecreases may comprise increasing or decreasing a variable transmitpower ratio. That is, there may be a baseline power control scheme thatexpresses the transmit power of the muting indicator commands relativeto a reference signal (pilot, control, etc.), which is directly powercontrolled based on reception quality feedback from the UEs 20. In suchcases, the base station 16 increases or decreases the transmit powerratio used for setting the power of the muting indicator transmissions,based on the reliability statistics.

As for producing those statistics, at least some of the UEs 20 areconfigured in one or more embodiments to report the receptionreliability results on an event basis, e.g., to send a report if thetotal number of unreliable commands exceeds a threshold. The thresholdmay be configured by the network, may be a pre-defined value or may beimplementation specifically at the UE 20. Each base station 16 also maybe configured to autonomously increase the power of the muting indicatorcommands, if the reported measurements exhibit large error. Note that anLTE eNodeB, as such a base station 16, could be configured to performsuch control in consideration on, e.g., the PDCCH Interference Impactparameter, which is signaled over the X2 interface between eNodeBs.

In one embodiment, when the lower-layer signaling can be decoded by a UE20 only in the serving cell 18, the network 10 ensures that no othercell 18 included in the assistance data sent by the network 10 mutesduring a given positioning occasion for the UE 20. This configurationprovides advantages for scenarios when a UE 20 can read low-layersignaling (e.g. control channels) only for its serving cell. In suchcases, the muting command only tells the UE that its serving cell (oralternatively, the reference cell) is muted or not. However, at least insome networks, even such limiting muting indications may be enough,because it at least allows the UE 20 to receive muting indications forthe presumably strongest interferers—i.e., the reference signalstransmitted in the serving or reference cell—and that can be sufficientto improve its measurements of reference signals from other cells. Asfor the other cells, the UE 20 may be configured to assume (if it has toassume anything) that they are not muted at the times its reference orserving cell is muted and it is left to the network implementation howto ensure that this UE assumption is correct, which is possible byensuring the separation in time/space of the reference signal muting inneighbor cells. So, in an example implementation, a UE whose referenceor serving cell is muted is informed before the muting occurs and it canuse that information to make strategic determinations as to when to makemeasurements for its neighboring cells.

As such assistance data to the UE 20 is typically provided bypositioning node 26, e.g. an E-SMLC in the LTE control plane, thepositioning node 26 is, in one or more embodiments, configured tocoordinate muting control across a set or subset of cells, to accomplishthe above-described control. Also, in such cases, the muting indicatorinforms the UE 20 about muting in the reference cell 18. Note that thereference cell 18 is not necessarily the UE's serving cell 18, but theUE 20 is aware of which cell 18 is considered to be the positioningreference cell 18, based on the positioning assistance informationreceived from the network 10.

Of course, in other embodiments described herein, the UEs 20 receive themuting configuration information based on a combination of lower-layerand higher-layer signaling. Such embodiments allow for (logically)combining the lower layer muting indicator commands with the higherlayer signaling, which may be, e.g., radio resource control (RRC),signaling, LTE positioning protocol (LPP) signaling, etc. Such combiningenables any given UE 20 to acquire more comprehensive information aboutthe muting applied in any given occasion in any given cell 18. As anexample, the lower-layer signaling provides the UE 20 with mutingindicator commands, indicating whether or not muting will be applied,while the higher layer signaling indicates the structure or arrangement,or other details, regarding the particular manner in which such mutingwill be applied. For example, as noted, the higher-layer signaling canbe used to indicate which subframes are muted and/or to indicate theparticular time and/or frequency resources to which muting is applied.In a specific example, the higher layer signaling conveys informationabout the muting bandwidth, which is the part of the configured RStransmission bandwidth over which the RS is temporarily not transmitted.

The configuration via higher layer signaling can be done in asemi-static manner, e.g. at a call setup or occasionally during thecall. Furthermore the higher layer configuration can be done by the basestations 16 (e.g., by eNodeBs in LTE) or by the positioning node 26(e.g., an E-SMLC in LTE), or by any other appropriately configured radionode in the network 10.

This arrangement allows the use of higher-layer signaling protocols tobe used to carry static or semi-static information about the particularmanner in which muting will be applied, while the more dynamic signalingof the muting indicators is done via lower-layer signaling, where thoseindicators indicate the selective application of muting to givenreference signal transmission occasions. In other words, higher-layersignaling can be used to indicate how muting is applied—this can beunderstood as configuring the reference signal operations of the UEs 20or other receiving radio equipment, to accommodate the particularstructure of reference signal muting that will be used—and lower-layersignaling is then used to indicate when muting is applied.

A specific example comprises using higher-layer signaling to indicatethat muting is applied only to the first half of subframes within anygiven reference signal occasion, or that muting is applied only to thefirst two subframes within any given occasion, etc. Further, as arefinement of this method, it is contemplated herein that a number ofpredefined muting configurations can be identified, with each suchidentity identifying a specific subframe muting arrangement, mutingbandwidth configuration, etc.

With this approach, the signaling overhead is reduced by signaling themuting configuration ID or IDs, which are known to the UEs 20 or otherreceiving radio equipment. That is, rather than signaling the actualconfiguration information, the network 10 signals the mutingconfiguration ID, and the UEs 20 or other receiving radio equipment usethat signaled ID to look up the particulars of the muting configuration,such as held in a memory-retained data structure (e.g., look-up table),which stores muting configuration details indexed by mutingconfiguration ID.

Regardless of the particular implementation details for such combinedsignaling, one advantage using a combination of higher-layer andlower-layer signaling is the flexibility thereby obtained; namely, UEs20 are informed both about the reference signal occasions to whichmuting is applied, and further informed about the particular manner inwhich such muting is implemented, e.g., the subframes and the mutingbandwidth that are muted in the involved occasion. Notably, suchinformation can be provided on a per-cell basis, via signalingoriginating from or otherwise flowing through the base stations 16 thatserve the involved cells 18.

Further, using higher-layer signaling, detailed muting configurationinformation can be sent, e.g., in conjunction with other, relatedinformation. For example, in the case where PRSs and positioningoccasions are at issue, higher-layer signaling can be used to sendpositioning assistance information, and to send muting configurationinformation in conjunction with or as part of that positioningassistance information. As noted, such signaling may occur over logicallinks between a UE 20 and a positioning node 26, where a logical linkmay comprise more than one physical link and can be represented, forexample, by the LTE Positioning Protocol (LPP). When signaled over LPP,the muting configuration information could be included, for example, asa part of the following information elements: OTDOA-ReferenceCellInfoand OTDOA-NeighborCellInfo, which comprise the OTDOA assistanceinformation for the reference cell and a neighbor cell, respectively.

In addition to communicating muting configuration information to the UEs20, at least some aspects of the muting configuration are agreed uponbetween the base station 16 and the positioning node 26. (In an LTEexample, such signaling can be done between an eNodeB and an E-SMLCusing the standardized LPP Annex (LPPa) protocol.) Depending on wherethe muting configuration is decided in the network 10 (e.g., at theE-SMLC, or at the eNodeB), the muting information is transmitted eitherfrom the base station 16 to the positioning node 26, or in the oppositedirection. Further, if the muting configuration is decided in some otherpart of the network 10, the positioning node 26 and/or the base station16 are configured to receive that information directly or indirectlyfrom that other node.

Further, the proposed signaling may be implemented in the control planeor in the user plane, and, as noted, the determination of the mutingconfiguration can be determined for or at each cell 18 independent (percell basis), or determined cooperatively across a number of cells 18,e.g., across given neighboring cells 18. Regardless, each cell 18transmits the muting configuration information applicable to it. Forresource efficiency, however, one or more embodiments contemplate notsignaling muting configuration information when muting is, in general,not used within the cell 18. (This is different than the case wheremuting is in general use within the cell 18, but is selectively appliedor not applied to given reference signal occasions.) Correspondingly,UEs 20 that are configured to otherwise receive and process mutingconfiguration information can be programmed or otherwise configured tointerpret the absence of muting configuration information from a givencell 18 as meaning that muting is not in use for that cell 18.

Broadly, the present invention proposes one or more methods andapparatuses which avoid the necessity of using a long-termpre-determined, and/or statically fixed muting pattern, and avoidslocking the network 10 into sub-optimal pattern variations (such as areimposed by cell-specific randomization of muting). Instead, with thepresent invention and its ability to efficiently determine, control,coordinate, and signal muting configuration details, the network 10 isfree to decide what particular muting configuration is best, at anygiven time, or for any given area or areas of the network 10.Furthermore, the UE is also informed about the muted PRS and thus has apossibility to optimize the measurement process and achieve bettermeasurement accuracy, at a complexity lower than it would be requiredwithout muting signaling.

As contemplated in one or more embodiments, the muting configuration ischaracterized by at least one of the following parameters or anycombination of them: muting bandwidth; the number of consecutivesubframes to which muting is applied, and a muting occasion index. In atleast one embodiment, the muting bandwidth is the part of the configuredRS transmission bandwidth over which the RS is temporarily nottransmitted.

In LTE, for example, PRS transmission bandwidth is typically configuredwith respect to the system bandwidth center, so one embodiment hereinapplies the same rule for muting bandwidth configuration, i.e. themuting bandwidth parameter indicates a given number X of muted resourceblocks (RBs), which are assumed to be located at the center of the PRSbandwidth, and are assumed to be blanked in a given positioning occasionor for a given period. (Refer again to FIG. 8.) If the muting bandwidthis not signaled, the UE may assume that muting is applied over theentire PRS transmission bandwidth.

In principle, there is no limitation on the muted PRS bandwidth, exceptthat it cannot exceed the PRS transmission bandwidth. However, to avoidthe centering problem, it makes sense to require that the differencebetween the system bandwidth and the muting bandwidth is an even numberor zero (the same actually applies for the difference between the systembandwidth and the PRS transmission bandwidth).

In one embodiment, it is also possible to mute PRS over the X/2 edgeRBs, as taken from each end of the configured PRS transmissionbandwidth. This may be achieved, for example, by signaling X with aminus sign. (Refer again to FIG. 9, to see an example of edgewisemuting. Note that muting edges of the PRS transmission bandwidth in ashort-term may look similar to reducing PRS transmission bandwidth.However, changing the actual PRS transmission bandwidth would requirere-transmission of positioning assistance data with the adjustedbandwidth. (Changing back to the original bandwidth would require yetmore signaling.) Thus, the muting bandwidth control via the mutingparameter is a more efficient approach.

As for the muting parameter indicating the number of consecutivesubframes to which muting applies, according to the current LTEstandards for PRS, the maximum defined number of consecutive subframesto be used for PRS transmission in one positioning occasion is six. Whenall these subframes are configured for positioning, it may or may not benecessary to apply muting over the entire positioning occasion. Thepresent invention advantageously allows for the efficient signaling ofwhich particular subframes are muted and/or where muting is appliedwithin a given positioning occasion.

As a default for one or more embodiment, when the number of consecutivemuted subframes is not signaled, the UEs 20 are configured to assumethat PRSs are muted in the corresponding cell over the entirepositioning occasion indicated for muting (no matter how manypositioning subframes it spans over). Otherwise, the signaled numbershall apply. In any case, in one or more embodiments, one bit is usedfor this parameter. For example, “0” means that the first N_(PRS)/2 setof positioning subframes are muted during the positioning occasionindicated for muting, e.g. the first 3 subframes out of 6 subframesduring a positioning occasion having 6 subframes in total. Conversely, a“1” means that second N_(PRS)/2 set of positioning subframes are mutedduring the positioning occasion indicated for muting, e.g. the last 3subframes out of the 6 subframes. In such embodiments, the PRS mutingsubframe offset with respect to the first subframe of the positioningoccasion is either zero or N_(PRS)/2.

As for the muting occasion index, it has been shown in 3GPP RAN4 studiesthat four positioning occasions are sufficient in most cases fordetecting a single cell, even under a pessimistic network configuration(asynchronous network, smallest bandwidth). Thus, as one non-limitingexample, the muting configuration can be set so that positioningoccasions are muted according to a periodicity of four.

More generally, it is assumed that one out of a larger number ofoccasions is muted, and that such an arrangement applies to recurringoccasions so that the muting periodicity is known. For example, assumingthat the muting periodicity spans four occasions, two bits can be usedfor signaling the muting occasion index, wherein: 00 means muting in thefirst positioning occasion, 01 means muting in the second positioningoccasion, 10 means muting in the third positioning occasion, and 11means muting in the fourth positioning occasion.

If one represents the muting periodicity as T_(MPRS), then one may viewthe muting occasion index as representing an occasion offset relative tothe start of each new muting period. That is, representing the mutingoccasion index as Δ_(MPRS), one sees that Δ_(MPRS)ε{0, 1, . . . ,T_(MPRS-1)}. With respect to 3GPP TS 36.211, Evolved UniversalTerrestrial Radio Access (E-UTRA); Physical channels and modulation,T_(MPRS) is defined as the reference signal periodicity in subframes,and Δ_(MPRS) indicates the reference signal subframe offset.

Thus, in one embodiment, the muting configuration information signaledfrom a given cell 18 includes a value for T_(MPRS), which indicates theperiodicity of muting—e.g., muting applied every X reference signaloccasions—and a value for Δ_(MPRS), which indicates the particularoccasion within the set of occasions spanned by that period to whichmuting is applied.

Further, while the present invention provides the network 10 with theability to dynamically adopt or revise muting configurations inindividual cells 18, and across groups of cells 18, it still may bedesirable to define a limited set of muting configurations and specifythem as muting patterns which could be standardized.

Further, it is proposed for one or more embodiments herein to define theRS muting configuration index as various combinations of Δ, Δ_(MPRS) andT_(MPRS) which satisfy the following equation:(10×n _(f) +└n _(s)/2┘−ΔT _(PRS)·Δ_(MPRS))mod(T _(PRS) ·T _(MPRS))=0,where Δ is set to a desired offset value, and n_(f) and n_(s) are thesystem frame number and the slot number within a radio frame,respectively. FIG. 10 depicts a table 1 illustrating examples oftabulated RS muting configuration indexes I_(MPRS), derived under theassumption that muting applies to either the first or the second half ofthe positioning occasion indicated for muting (i.e. Δ takes values Δ₁and Δ₂).

With the above in mind, the present invention in its various embodimentsoffers a number of advantages. Non-limiting example advantages include:flexible muting configuration with simple signaling; no need forpre-defined PRS muting patterns; reduced UE complexity, processing,power consumption, simultaneous with improved reference signalmeasurement performance. In part, the reduced UE complexity stems fromthe need for blind detection at the UE (since the present inventionprovides the UE with knowledge of when/where muting is used).

Further, as noted, the present invention can be implemented usingcontrol-plane based operations, or based on user plane and/or UEoperations, or combinations of these approaches. Furthermore, whilecertain aspects of the present invention have been highlighted in thespecific context of PRSs, the present invention is directly applicableto other types of reference signals, which may or may not be used forpositioning measurements.

Finally, modifications and other embodiments of the disclosedinvention(s) will come to mind to one skilled in the art having thebenefit of the teachings presented in the foregoing descriptions and theassociated drawings. Therefore, it is to be understood that theinvention(s) is/are not to be limited to the specific embodimentsdisclosed and that modifications and other embodiments are intended tobe included within the scope of this disclosure. Although specific termsmay be employed herein, they are used in a generic and descriptive senseonly and not for purposes of limitation.

What is claimed is:
 1. A positioning node for use with a wirelesscommunication network, said positioning node comprising: one or moreprocessing circuits configured to determine a muting configuration usedby one or more base stations for controlling muting of positioningreference signals transmitted at recurring positioning occasions by theone or more base stations to radio equipment in the wirelesscommunication network, the one or more processing circuits beingconfigured to determine the muting configuration from signaling receivedfrom the one or more base station; and a communication interfaceoperatively associated with the one or more processing circuits andconfigured to perform: receiving the signaling from the one or more basestations; and sending corresponding muting configuration information ashigher-layer signaling for receipt by the radio equipment receiving thepositioning reference signals from the one or more base stations;wherein the muting configuration information includes a bandwidthparameter identifying the portion of positioning reference signalbandwidth to which muting applies and a muting occasion parameterindicating positioning occasions to which muting applies; and whereineach of the positioning occasions comprises two or more consecutivesubframes that repeat at a predetermined periodicity.
 2. The positioningnode of claim 1, wherein the communication interface is furtherconfigured to send muting control signaling to the one or more basestations, to control positioning reference signal muting by said one ormore base stations, in accordance with the muting configuration.
 3. Thepositioning node of claim 1, wherein the positioning node is configuredto generate the muting configuration information to indicate when or howmuting will be applied by the one or more base stations, for indicatedor known positioning occasions, and to send at least a portion of themuting configuration information as higher-layer signaling, fortransmission by the one or more base stations to the radio equipmentreceiving the positioning reference signals.
 4. The positioning node ofclaim 1, wherein the one or more processing circuits are configured tocontrol muting of the positioning reference signals in coordinatedfashion across two or more cells of a radio access network, said two ormore cells associated with said one or more base stations, and whereinthe muting control signaling sent by the positioning node is configuredto effect coordinated muting control across the two or more cells. 5.The positioning node of claim 4, wherein the one or more processingcircuits are configured to coordinate, as across the two or more cells,at least one of the following: the timing or selection of whichpositioning occasions have muting applied to them; the positioningreference signal bandwidth to which muting is applied in one or morepositioning occasions; and the number of consecutive subframes to whichmuting is applied within a given positioning occasion.
 6. A method at apositioning node, for use within a wireless communication network, saidmethod comprising: determining a muting configuration, used by one ormore base stations for controlling muting of positioning referencesignals transmitted at recurring positioning occasions from the one ormore base stations to radio equipment in the wireless communicationnetwork, by receiving signaling from the one or more base stations, anddetermining the muting configuration of the one or more base stationsfrom said received signaling; and sending the muting configurationinformation as higher-layer signaling for receipt by the radio equipmentreceiving the positioning reference signals; wherein the mutingconfiguration information includes a bandwidth parameter identifying theportion of positioning reference signal bandwidth to which mutingapplies and a muting occasion parameter indicating positioning occasionsto which muting applies; wherein each of the positioning occasionscomprise two or more consecutive subframes that repeat at apredetermined periodicity.
 7. The method of claim 6, further comprisingsending muting control signaling to the one or more base stations, tocontrol positioning reference signal muting by said one or more basestations, in accordance with the muting configuration.
 8. The method ofclaim 6, further comprising generating the muting configurationinformation such that it indicates when or how muting will be applied bythe one or more base stations, for indicated or known positioningoccasions, and sending at least a portion of the muting configurationinformation as higher-layer signaling, for transmission by the one ormore base stations to radio equipment receiving the positioningreference signals.
 9. The method of claim 6, wherein said muting controlsignaling coordinates muting of the positioning reference signals acrosstwo or more cells of the wireless communication network, wherein the twoor more cells are associated with the one or more base stations.
 10. Themethod of claim 6, wherein the muting control signaling is generated tocoordinate at least one of the following across the two or more cells:the timing or selection of which positioning occasions have mutingapplied to them; the positioning reference signal bandwidth to whichmuting is applied in one or more positioning occasions; and the numberof consecutive subframes to which muting is applied within a givenpositioning occasion.
 11. A method in a radio apparatus of controllingmeasurement of positioning reference signals that are transmitted by awireless communication network at recurring positioning occasions, saidmethod comprising: receiving signaling from the wireless communicationnetwork that conveys the following muting parameters: a bandwidthparameter identifying the portion of positioning reference signalbandwidth to which muting applies, and a muting occasion parameterindicating positioning occasions to which muting applies, wherein eachof the positioning occasions comprises two or more consecutive subframesand the positioning occasions recur at a pre-set periodicity; andcontrolling positioning reference signal measurement by the radioapparatus, in accordance with the received muting parameters.
 12. Aradio apparatus comprising: a receiver configured to receive positioningreference signals transmitted from a wireless communication network atrecurring positioning occasions, and to receive signaling from thewireless communication network that conveys the following mutingparameters that define a muting configuration used by the wirelesscommunication network for muting the positioning reference signals inone or more cells of the wireless communication network, said mutingparameters including: a bandwidth parameter identifying the portion ofpositioning reference signal bandwidth to which muting applies; and amuting occasion parameter indicating positioning occasions to whichmuting applies, wherein each of the positioning occasions comprises twoor more consecutive subframes and the positioning occasions recur at apre-set periodicity; and one or more processing circuits that areoperatively associated with the receiver and are configured to controlpositioning reference signal measurement by the radio apparatus, inaccordance with the received muting parameters.
 13. The positioning nodeof claim 1, wherein the muting configuration information furtherincludes a subframes parameter indicating the number of consecutivesubframes within a positioning occasion to which muting applies.
 14. Themethod of claim 6, wherein the muting configuration information furtherincludes a subframes parameter indicating the number of consecutivesubframes within a positioning occasion to which muting applies.
 15. Themethod of claim 11, wherein the muting occasion parameter indicateswhether muting will be used in an indicated or known muting occasion.16. The radio apparatus of claim 12, wherein the muting occasionparameter indicates whether muting will be used in an indicated or knownmuting occasion.